The Coronary Drug Project was initiated in 1965, primarily to answer the prevailing question about the safety and efficacy of long term use of various cholesterol lowering agents in patients with coronary artery disease. The Coronary Drug Project was a randomized, double-blind, placebo-controlled study, conducted between 1966 and 1975. It was designed to evaluate the efficacy and safety of five lipid-modifying drugs in 8,341 men, with a history of prior myocardial infarction (MI). Niacin, clofibrate, dextrothyroxine, and two estrogen regimens were evaluated in the study along with a placebo arm.43, 44 DT4 was administered at 6.0 mg /day. The primary endpoint was overall mortality at 5 years. After a mean follow-up of 36 months, because of a nonsignificant trend toward higher mortality in the DT4 arm compared with placebo, the DT4 arm was discontinued.